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JPH09200891

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DESCRIPTION JPH09200891
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker used in a television receiver or the like.
[0002]
2. Description of the Related Art In recent years, with the spread of television receivers such as
high vision and wide vision, the screen of the television receiver is becoming generally wide.
However, on the other hand, narrow and thin ones as a set are desired from the housing situation
in Japan.
[0003]
A speaker for a television receiver is usually attached to both sides of a cathode ray tube, which
contributes to increasing the width of the television receiver, and a rectangular or elliptical
speaker having a long and narrow structure is used. It has In addition, the horizontal width of the
cathode ray tube is required to further narrow the width of the speaker, and at the same time,
high sound quality corresponding to the high image quality of the screen is required, and a trackshaped elongated speaker is adopted It has become like that.
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[0004]
A conventional track-shaped elongated speaker will be described with reference to FIGS. 3 (a) to
3 (c) and FIG. Fig. 3 is a structural view of a conventional track-shaped elongated speaker, and
Fig. 3 (a) is a plan view, Fig. 3 (b) is a side sectional view in the major axis direction, and Fig. 3 (c)
is a minor axis direction. FIG. 4 is a side sectional view, and FIG. 4 is a frequency characteristic
view. In the figure, a diaphragm 1b is an elongated diaphragm which generates air vibration, and
an edge 2b is joined to an outer peripheral portion of the diaphragm 1b and held by a frame 5b.
[0005]
A voice coil bobbin 3b is fixed to the central portion of the diaphragm 1b, and is held by the
frame 5b in a freely vibrating manner via a damper 4b. On the other hand, a magnetic circuit 10
including a yoke 8b, a magnet 7b and a plate 6b is provided in the central recess of the frame 5b.
Then, the voice coil wound around the voice coil bobbin 3b is held in the air gap of the magnetic
circuit 10, and the voice coil bobbin 3b moves in a piston by the drive current, and the
diaphragm 1b vibrates in that direction. As a result, sound waves are emitted from the diaphragm
1b.
[0006]
FIG. 4 shows the frequency characteristic of the reproduction sound pressure level of this
speaker, and the vertical axis shows the posture sound pressure level at a point of 1 m on the
front axis when 1 W is input to this speaker, and the horizontal axis shows the drive Indicates the
frequency.
[0007]
SUMMARY OF THE INVENTION However, the conventional loudspeaker as described above has
the following problems.
That is, since the driving method is adopted in which the central portion of the elongated
diaphragm 1b is point driven, split resonance in the long axis direction is likely to occur. As a
result, in the mid-high range, peak-dip occurs in the frequency characteristic of the reproduction
sound pressure, resulting in deterioration of the sound quality. For example, on the
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characteristics shown in FIG. 4, noticeable dips are seen at 2 kHz, 3 kHz and 5 kHz.
[0008]
Further, the width of the drive system including the magnetic circuit 10 and the voice coil bobbin
3b needs to be smaller than the length of the short diameter of the speaker, and it is physically
impossible to increase the diameter of the voice coil bobbin 3b. The line length L can not be
made longer. Further, since the volume of the magnet 7b is also limited to a small size, the
magnetic flux density B of the air gap can not be sufficiently secured.
[0009]
As a result, the force coefficient (B × L) of the drive system becomes small, making it difficult to
increase the conversion efficiency. Further, the radius of curvature and width of the damper 4b
decrease so as to be accommodated inside the frame 5b, and as a result, the stiffness of the
vibration system increases, the minimum resonance frequency fo increases, and it becomes
difficult to reproduce the low frequency range. Had.
[0010]
The present invention has been made in view of such conventional problems, and it is difficult to
cause split resonance while having a narrow width (elongated structure), and flat frequency
characteristics can be obtained, conversion efficiency is improved, and minimum resonance is
achieved. It is an object of the present invention to provide a speaker having an excellent sound
quality that enables low frequency reproduction with a low frequency fo.
[0011]
SUMMARY OF THE INVENTION In order to solve the above problems, according to the present
invention, the planar shape seen from the direction of vibration is non-axisymmetric with a major
axis and a minor axis and opposite to the direction in which sound is emitted. A reverse domeshaped diaphragm having a bulge, and a voice coil bobbin formed in a band shape parallel to the
vibration direction along the outer peripheral portion of the diaphragm and having a bandshaped upper end bonded to the outer peripheral portion of the diaphragm; The voice coil
bobbin has the same non-axisymmetric shape as the diaphragm by configuring the speaker with
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the voice coil wound around the outer peripheral surface of the voice coil bobbin and the
magnetic circuit giving the magnetic flux for vibration to the voice coil. By driving the whole of
the diaphragm, the inverse dome-like diaphragm having a bulge in the direction opposite to the
direction of sound emission can greatly reduce the air deduction amount on the front surface and
lower the lowest resonance frequency fo, and can reproduce It is possible to above.
Furthermore, the wire length of the voice coil is considerably longer than that of the conventional
one, and the volume of the magnet can be increased, so that the driving force can be increased.
[0012]
The invention according to claim 1 of the present invention is characterized in that the planar
shape seen from the vibration direction is non-axisymmetric with a major axis and a minor axis
and opposite to the direction in which sound is emitted. A diaphragm having a reverse dome
shape having a bulge, a voice coil bobbin formed in a band shape parallel to a vibration direction
along an outer peripheral portion of the diaphragm and having a band-like upper end bonded to
the outer peripheral portion of the diaphragm; It consists of a voice coil wound around a voice
coil bobbin and a magnetic circuit that applies a magnetic flux for vibration to the voice coil, and
the shape of the voice coil bobbin is axisymmetric with the same shape as the diaphragm, and the
diaphragm is The whole is driven, and as the inverted dome shaped diaphragm, the air removal
amount on the front surface of the diaphragm is increased to lower the minimum resonance
frequency fo, the wire length of the voice coil is also long, the magnet is also enlarged and the
driving force is large. it can Than is.
[0013]
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1
(a) to 1 (c) and FIG.
1 (a) is a plan view, FIG. 1 (b) is a side sectional view in the major axis direction, FIG. 1 (c) is a
side sectional view in the minor axis direction, and FIG. 2 is a frequency characteristic diagram
measured under the same conditions as FIG. In the figure, 11a is a non-axisymmetric shape
having a major axis and a minor axis in plan view seen from the direction of vibration, and an
inverted dome shaped diaphragm having a bulge opposite to the direction of emitting sound. 12a
is an edge joined to the outer peripheral portion of the diaphragm 11a, and the edge 12a is held
by the frame 15a. A magnetic circuit 20 is assembled to the bottom of the frame 15a, and
comprises a yoke 18a, a magnet 17a, a plate 16a and the like.
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[0014]
A dustproof net 19a is mounted on the frame window of the frame 15a to prevent dust from
entering the magnetic circuit 20. A voice coil bobbin 13a is formed in a strip shape (track shape)
parallel to the vibration direction along the outer peripheral portion of the diaphragm 11a and is
joined to the outer peripheral portion of the diaphragm 11a. A voice coil is wound at a position
corresponding to the magnetic gap 20a of.
[0015]
In the present invention, a non-axisymmetric (track-shaped) diaphragm having a major axis and a
minor axis prevents split resonance as shown in FIG. 2 and obtains flat frequency characteristics
in the middle to high range and reverse The dome shape makes it possible to improve the bass
characteristics, and by making the voice coil bobbin of the same shape as the diaphragm, the
wire length of the voice coil can be made longer, the magnet can be enlarged and the driving
force can also be made larger.
[0016]
A wide directivity characteristic can also be obtained by forming the diaphragm 11a in an
inverted dome shape.
[0017]
Also, the conventional damper has been eliminated.
[0018]
As described above, the present invention makes it possible to provide a speaker that is excellent
in bass characteristics and flat in the middle to high frequency sound pressure frequency
characteristics, and is used for a television receiver. In this case, the television receiver can be
made to have excellent sound quality characteristics without widening the width.
[0019]
Brief description of the drawings
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[0020]
FIG. 1A is a plan view of a speaker according to an embodiment of the present invention.
[0021]
Fig. 2 Frequency characteristics of same sound pressure level
[0022]
Fig. 3 (a) A plan view of a conventional speaker
[0023]
Fig. 4 Frequency characteristics of same sound pressure level
[0024]
Explanation of sign
[0025]
11a diaphragm 12a edge 13a voice coil bobbin 20 magnetic circuit
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